1. Field of the Invention
The present invention relates to a production method of and a production apparatus for an optical recording disc comprising two round substrates bonded with each other.
2. Description of the Related Art
With reference to FIGS. 1A to 1E, a conventional production method of an optical recording disc will be explained. As shown in FIG. 1A, a second round substrate having 120 mm in diameter (made from, for example, polycarbonate) D2 is prepared. h2 is the center hole of the second round substrate D2. r2 is the recording surface of the second round substrate D2, with a data recording trace (comprising pit rows with different lengths and widths) formed concentrically or along a track tantamount to a circle.
As shown in FIG. 1B, while rotating the second round recording plate D2, an ultraviolet ray curing type resin R as an adhesive is dropped onto the recording surface r2 at an appropriate position in the range of 15 mm to 50 mm in radius on the recording surface r2 of the second round recording plate D2 so as to apply the ultraviolet ray curing type resin R in a ring-shape with a predetermined width substantially concentric with the second round substrate D2.
As shown in FIG. 1C, a first round substrate having a 120 mm diameter (made from, for example, polycarbonate) D1 is prepared. h1 is the center hole of the first round substrate D1. r1 is the recording surface of the first round substrate D1, with a data recording trace (comprising pit rows with different lengths and widths) formed concentrically or along a track close to a circle.
As shown in FIG. 1D, the recording surfaces r1, r2 of the first and second substrates D1, D2 are superimposed via the ultraviolet ray curing type resin R for uncured bonding so as to obtain an optical recording disc. The optical recording disc obtained by the uncured bonding is rotated at a high speed so as to spread the ultraviolet ray curing type resin R between the first and second round substrates D1, D2 to the whole portion of the inner peripheral part and the outer peripheral part by a centrifugal force so as to have an even thickness to thereby obtain an uncured bonded optical recording disc D.
As shown in FIG. 1E, by irirradiating an ultraviolet ray to the optical recording disc D comprising the first and second round substrates D1, D2 obtained by the uncured bonding via the ultraviolet ray curing type resin R spread in FIG. 1D for curing the ultraviolet ray curing type resin R, the first and second round substrates D1, D2 are bonded so as to provide a completed optical recording disc D.
According to the conventional production method of an optical recording disc, since the ultraviolet ray curing type resin R dropped on the second round substrate D2 is spread so that the contact starting area of the ultraviolet ray curing type resin R with respect to the first round substrate D1 is wide, a great problem arises in that large numbers of bubbles generate in the ultraviolet ray curing type resin R so that the large numbers of the bubbles remain in the cured ultraviolet ray curing type resin R of a completed optical recording disc to thereby deteriorate the quality of the optical recording disc.
The present invention is to provide a production method of and a production apparatus for an optical recording disc comprising two bonded round substrates, capable of obtaining a high quality optical recording disc by drastically reducing the number of bubbles remaining in an adhesive of the completed optical recording disc.
Moreover, the present invention is to provide a production method of and a production apparatus for an optical recording disc comprising two bonded round substrates, capable of obtaining a high quality optical recording disc by drastically reducing the number of bubbles remaining in a cured ultraviolet ray curing type resin of the completed optical recording disc.
A first aspect of the present invention is a production method of an optical recording disc comprising the steps of applying an adhesive on a predetermined position of the upper surface of a first round substrate, reversing the first round substrate applied with the adhesive, and bonding the reversed first round substrate and a second round substrate with each other via the adhesive on the first round substrate so as to obtain an optical recording disc.
According to the first aspect of the present invention, an optical recording disc is obtained by applying an adhesive on a predetermined position of the upper surface of a first round substrate, reversing the first round substrate applied with the adhesive, and bonding the reversed first round substrate and a second round substrate with each other via the adhesive on the first round substrate.